Paper forming section



April 14, 1959 v R. J. THOMAS 2,881,663

' PAPER FORMING SECTION Filed March so, 1956 2 Sheets-Sheet 1 @ZQZZZQE Ai y/A4440 (/4/755 25 0/7/45 April 14, 1959 R. J. THOMAS 1,

- PAPER FORMING SECTION Filed March 50, 1956 2 Sheets-Sheet 2 @522 i QC A /44w Jwzs Zs ww 45E &

United States Patent PAPER FORMING SECTION Reginald James Thomas, Somerset, England, assignor to St. Annes Board Mill Company, Limited, Bristol, England, a corporation of Great Britain Application March 30, 1956, Serial No. 575,154

7 Claims. (Cl. 92-38) This invention relates to method and apparatus for de-watering pulp or stock to effect the formation of webs wherein the stock is fed to rolls having forming wires trained thereover. More particularly, this invention deals with a paper making machine and a method of making paper wherein initial de-watering of paper stock includes upward as well as downward discharge of water through the coacting traveling wires under the influence of rolls having open cellular peripheries. Still more particularly, stock is fed to upper and lower cellular faced rolls having forming wires trained thereover, wherein one roll and wire may be positioned up-wire, down-wire, or in directly opposed relation to the other roll and wire.

In accordance with the present invention, the method and apparatus hereinafter described are embodied in the so-called wet end of a paper-making machine which initially de-waters the dilute paper stock to form a fibrous web. Top and bottom forming wires are trained around cellular-faced rolls which are positioned to define an inlet gap for receiving dilute aqueous paper stock. The cellular faces of the rolls are provided with forming areas that may or may not be suctionized to aid in the removal of Water from the stock, and to effect initial de-watering of a stock and the formation of a web before the forming wires leave the rolls. The suction area of the rolls may be circumferentially adjustable. This enables the overall length of the machine to be appreciably decreased. This also permits the installation of additional drying capacity within the original length of the machine, if desired. Paper machines equipped with wet ends according to the present invention include pressing arrangements and the mechanisms which will de-water the layer of stock after it has been initially set into web form so as to render the layer self-supporting and capable of being removed from the main forming wire after relatively short length of travel thereon.

Accordingly, it is an object of this invention to provide a method and apparatus for de-watering pulp or stock for forming a web at the wet end of a paper forming machine.

Another object of this invention is in the provision of means at the wet end of a paper-making machine which will effect initial de-watering of stock for forming a web within a very short length of the forming wire thereby appreciably decreasing the overall length of the machine or accommodating installation of additional drying capacity within the original length of the machine.-

A further object of this invention resides in the provision of means at the wet end of a paper making machine for initially de-watering paper stock in forming a web which includes a pair of coacting or offset cellular faced rolls having forming wires trained thereover.

A still further object of this invention is to provide means at'the wet end of a paper-making machine'for initially de-watering paper stock in the formation of a web which includes a pair of vertically aligned coacting rolls having forming wires trained thereover, wherein the rolls ICE have open cellular peripheries that may or may not be suctionized in the forming area.

Another object of this invention is to provide web formation by feeding stock to upper and lower cellular faced rolls having forming wires trained thereover, wherein the one roll and wire may be displaced up-wire, down-wire, or in directly opposed relation to the other roll and Wire.

A still further object of this invention is in the provision of means at the wet end of a paper-forming machine which is capable of providing upward and downward de-watering of stock to effect web formation.

Other and further objects of this invention will be apparent to those skilled in this art from the following detailed description of the annexed sheets of drawings which, by way of preferred examples, illustrate several embodiments of the invention.

On the drawings:

Figure 1 is a somewhat diagrammatic side elevational view of the wet end of apaper-making machine according to this invention;

Figure 2 is a greatly enlarged somewhat diagrammatic side elevational view of the coacting cellular faced rolls provided at the wet end of the machine in Figure 1;

Figure 3 is an enlarged somewhat diagrammatic side elevational view, similar to Figure 2, but illustrating another embodiment of the invention;

Figure 4 is a greatly enlarged detail view, in section, taken radially through one of the rolls shown in Figures 2 and 3 to illustrate the cellular construction of these rolls;

Figure 5 is a fragmentary sectional view, taken substantially along line V-V of Figure 4.

As shown on the drawings:

Referring particularly to Figure l, the paper-making machine of the instant invention has its wet end as indicated by the numeral 10, and includes a base frame 11 and an overhead frame 12. The base frame 11 is supported above a floor or horizontal surface 13 by suitable columns 14, while the overhead frame 12 is upwardly spaced and parallel aligned with the base frame and supported therefrom by suitable columns 15.

An endless main or bottom forming wire 16 is looped around a breast or first roll 17 having an open cellular face or periphery, supporting rolls a and b, a couch roll 18 and guide rolls 19 carried on pedestals 20, so as to have an elongated substantially horizontal upward run between the couch and breast rolls.

An upper forming wire 21 is trained around an adjustable on-coming roll 22 vertically aligned above the breast roll 17 and also having an open cellular periphery or face, an oflgoing roll 23, and guide rolls 24 carried on the overhead frame 12 by suitable pedestals 25, so as to provide an elongated substantially horizontal bottom run between the oncoming and ofigoing rolls for traveling coaction with the upper horizontal run of the main forming wire 16. The upper roll 22, in this instance is horizontally and vertically adjustable, while the lower roll 17 is stationary. Alternately, the lower roll 17 could be horizontally and vertically adjustable while the upper roll 23 is stationary.

A tension roll 26 mounted on a pedestal 27 cooperates with the guide rolls 19 to hold the wire 16 taut, while a tension roll 28 supported above the overhead frame 12 by a pedestal 29 holds the upper wire 21 taut.

Stock is delivered to the traveling wires 16 and 21 at the wet end through an inlet 30, having a lower side 30a and an upper side 30b, the inlet being positioned on the upturning side of the roll 17 and the downturning side of the roll 22. The inlet 30 may be in the form of a conduit as shown or, the upper side 30b may be eliminated to deliver an open top pond or layer of stock to the wires. In the first embodiment shown in Figure 2, the upper horizontal run of the bottom forming wire 16 and the lower horizontal run of the upper forming wire 21 are substantially parallel to one another to form therebetween a gap G as seen in Figure 2.

The embodiment of Figure 3 differs from that in Figure 2 in the arrangement of the rolls 17 and 22, which are offset from one another where the upper adjustable roll 22, with its forming wire 21 is positioned downwire from the lower roll 17. Further, the roll 22 will be preferably positioned substantially between vertical lines extending through the axes of the supporting rolls a and b or the breast roll 17 and the roll a as shown. While the roll 22 is shown as positioned downwire from the roll 17 it will be understood that it may be positioned upwire therefrom. Additionally, this embodiment provides a wedge shaped gap G between the traveling wires 16 and 21 which diminishes in height as it extends from the machine wet end. However, it will be understood that the gap between the wires in this embodiment may take the form of that shown in the embodiment of Figure 2; and the gap in Figure 2 may take the form of the embodiment of Figure 3. Additionally, a sloping slice 31 is arranged with its forward edge bearing against the lower run of the upper forming wire 21 to provide a pressure point facing in the direction of the stock inlet. This slice may be suctionized, if desired. Also such a slice arrangement may be similarly employed in association with the upper wire 21 in the embodiment of Figure 2. This slice constitutes a waterway above the bottom run of the top wire for removing water upwardly from the stock.

Initial de-watering of the stock and web formation is accomplished by the rolls 17 and 22, which function alike in each of the embodiments, and the construction of which is shown in detail in Figures 4 and 5.

Referring now to Figures 4 and 5, the lower roll or breast roll 17 will be described in detail, which is constructed in the same manner as the upper roll 22. The lower side 3th! of the stock inlet conduit 36 is positioned so that dilute paper stock is brought to the wire 16 at a point where the wire still finds direct support upon the roll 17. Formation of the web upon the wire occurs almost entirely between the forward leading edge of the lower stock conduit side 30a and the point at which the forming wire 16 leaves the roll 17, and this area will be hereinafter referred to as the forming zone.

In order to accommodate the required drainage of water from the dilute stock through the wire within the forming zone, and to facilitate removal of the drained waters, the outer periphery of the roll is open and provided with a plurality of annularly arranged and circumferentially spaced cells 32, the walls of which are defined by a series of radially disposed baflles or partitions 33. These partitions, in the present instance, are set into and project from a cylindrical shell 34 of the roll and are disposed in the axial direction so that the cells 32 extend longitudinally from one end of the roll to the other. In order to establish communication between the inner ends of the cells 32 and the interior of the roll, the shell is provided with a plurality of apertures 35, and it will be noted in Figure that these apertures 35 are arranged in closely set series extending longitudinally of the respective cells. Preferably, the outer end of each aperture is countersunk as illustrated. The outer edges of the partitions 33 are suitably notched to receive a wire 36 which extends helically around the roll from one end to the other. It will be understood that a plurality of wires may be used each embracing the periphery of the roll. As seen most clearly in Figure 5, the outer edges of the wire 36 are flush with the outer edges of the partitions 33; and these wires coact with the partitions to form a backing for a cover wire 37 of coarse mesh which embraces the roll and forms a suitable support for the forming wire 16.

As seen diagrammatically in Figure 2, the inside of the roll 17 is provided with a central vacuum chamber V connected to any suitable suction generating device. The

inside of the shell 34-may be subjected to a vacuum at certain areas A and B, wherein suitable means is provided for adjustably communicating the areas or chambers to the main vacuum chamber V. The chamber A is sealed to the inner wall of the shell 34 by sealing members 38 and 39, while the chamber B is sealed to the shell by the sealing member 39 and a sealing member 40. The suction in the vacuum chambers A and B is impressed through the apertures 35 upon the associated cells 32 within the areas confined by the sealing elements 38, 39 and 40. The strength of the suction in the primary area A may be regulated by an adjusting means, while the suction in the secondary area B may be independently regulated by another adjustment means. Additionally, the total scope of the combined suction areas may be circumferentially adjusted if desired.

Preferably, the suction chamber A is positioned so that it will act upon the cells 32 as they pass by the leading edge of the lower stock inlet wall 30a, while the vacuum area B terminates at a point substantially remote from where the forming wire 16 leaves the roll 17. And the separation between the areas A and B is substantially at the point where the forming wire 16 leaves the surface of the roll 17. As seen in Figure 2, the suction areas in the upper roll 22 are positioned substantially similar to that in the lower roll 17, wherein the suction area A is substantially oppositely aligned from the area A in the lower roll and the area B is substantially aligned oppositely from the area B in the lower roll. However the suction areas will be positioned so that they will give the best possible de-watering action and web formation.

The stream of dilute stock is delivered by way of the stock conduit 30 to the forming zones on the rolls 17 and 22 at a velocity which may or may not be the same as the speed of the forming wires. Drainage of the water through the Wires 16 and 21 result in web formations thereon, wherein upward formation take place. Regulated suctions may be applied to the wires within the forming zones as previously set forth, these suctions being suificient to supplement the stream pressure and to drain through the wires within the forming zones substantially all of the water of the stream necessary for proper web formation with the exception of a minor portion thereof which is permitted to flow on to the wire as the latter leaves the zone.

The water drained through the wires within the forming zones passes into the cells 32 of the rolls and these cells are made sufiiciently deep to afford a capacity within the cellular peripheral portion of the roll capable of accommodating the water of the stream without displacement of any substantial portion thereof into the interior of the roll. Preferably, the partitions or baffles 33 are constructed as thin as possible, consistent with the function of these elements to support the cover wire 37 and the forming wire 16, so that in flowing into the peripheral portion of the roll, the stream may remain substantially intact, as illustrated in Figure 4. To this end, it then is desirable that the depth of the cells does not exceed the upper and lower boundaries of the stream. It may be noted in Figures 2 and 3, that the lower wall 30a and the upper wall 30b of the stock conduit 30 are in substantial horizontal alignment with the depth of the cells. In some cases, it may be desirable to vary the relative depth of the streams and the cells. As each of the cells 32 leave the primary suction area A, they come immediately under the influence of the suction within the secondary area B. Within the secondary area B, the suction opposes centrifugal force tending to throw outwardly from the roll without, however, drawing the water into the interior of the roll. When the cells 32 pass from the influence of the secondary sucton area B, centrifugal force may then act without opposition to displace the water from the roll in a substantially tangential direction, as indicated in Figure 4, into the space between the upper and lower reaches of the corre- I sponding wire and into a save-all of the type conventionally employed in Fourdrinier machines. In this instance, a save-all 41 is provided for the lower roll 17 and a save-all 42 is provided for the upper roll 22.

At the high speeds of which the present invention is capable of operating, the dilute stock flows through the stock condiut 30 at a velocity which in accordance with known hydraulic principles effects turbulence of a character tending to distribute the fibers uniformly and in random disposition in the stream. Thus, the instant invention provides a method and machine for attaining excellent web formation at high operational speeds, and wherein the formation is upwardly and downwardly along the forming wires.

In the operation of the embodiment of Figure 3, stock is fed to the lower wire 16 while still supported on the lower roll 17 wherein downward de-watering takes place resulting in downward fibrous formation. In the instant case, the upper side 3% of the inlet extends to the periphery of the upper roll 22. However, it will be understood that the upper side 30b of the inlet may terminate opposite the termination point of the lower side 30a or it may be eliminated to provide an open top pond or layer of stock. As the stock is engaged by the upper wire 21 at the upper roll 22, upward de-watering thereof is effected resulting in upward fibrous formation on the upper wire. This will result in a staggering of the stock de-watering action and the downward and upward fibrous formations.

Subsequent to the upward fibrous formation, the coaction of the wires forces the fibrous formations together to form a unitary web having interlocked fibers.

Referring again to Figure 1, a plurality of press roll assemblies 43 are provided downstream from the cellular faced rolls 17 and 22. Each assembly 43 includes a bottom roll 44 in the loop ofthe main forming wire 16 and being supported on the base frame 11 by a pedestal 45, and a top roll 46 in the loop of the upper forming wire 21 and being adjustably supported from the overhead frame 12 by a pedestal 47. The rolls 44 and 46 cooperate to form a horizontal pressure nip squeezing the wires 16 and 21 toward each other. If desired, the presses 43 can be suction presses with suction boxes in either the roll 44 or 46, or in both of the rolls. The presses 43 serve to further squeeze the pulp that is formed on the wires to remove further amounts of water therefrom. The squeezed out water on the top of the wire 21 adjacent each press 43 can be removed with suction slices 48 which may be provided on the upstream or downstream side of each press 43.

Further, as to the embodiment of Figure 3, although not shown, by displacing the upper roll 22 ahead of the bottom roll 17, similar fibrous formations and interlocking thereof is elfected.

The coaction of the forming wires upon leaving the cellular faced rolls further serve to force the fibrous formations of each wire together to form a unitary web with interlocked fibers.

From the foregoing, it will therefore be understood that this invention provides method and apparatus for de-watering stock in the formation of fibrous webs, wherein the stock is initially de-watered by coacting or offset cellular faced rolls, which may or may not be suctionized, thereby reducing the overall length of a machine.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

I claim as my invention:

1. The method of making a fibrous web which comprises delivering a high velocity turbulent flow of dilute watery unformed fibrous stock to a narrow elongated tapering gap defined by upper and lower coacting web forming wires, moving the wires toward the narrow end of the tapering gap, supporting the wires at the entrance mouth of the gap upstream from the narrow end of the gap on opposed foraminous 'rolls, draining water from the stock through the wires into said rolls to deposit fibers in random dispersed condition on both wires, continuing draining water from the stock along the length of said gap, building up a web on both wires from the turbulently flowing stock between the wires as the wires advance to the narrow end of the gap, evacuating said rolls along the entrance mouth of said gap to accelerate drainage through the wires into the rolls, pressing the wires together downstream from the narrow end of said gap, and removing further amounts of water from the web.

2. The method of making a fibrous web which comprises delivering a high velocity turbulent flow of dilute watery unformed fibrous stock to a narrow elongated tapering gap defined by upper and lower coacting webforming wires, moving the wires toward the narrow end of said gap, supporting the wires at the entrance mouth of the gap and upstream from the narrow end of the gap on top and bottom rolls having open cellular peripheries adapted to convey water from the entrance mouth of the gap, draining water from the stock in said gap through said wires into the cells of said rolls as the cells travel along the top and bottom of the entrance mouth to deposit fibers from said stock in random dispersed condition on both of said wires, evacuating said rolls along said entrance mouth of the gap to hold water in said cells as the cells advance into the gap and centrifugal force tends to discharge the water out of the cells, separating the wires from the rolls, discharging water outwardly through the rolls from said cells away from said wires, collecting the discharged water from the cells to prevent rewetting of the wires, squeezing the wires toward each other to interlock the fibers deposited thereon and form a unitary web between the wires, and further de-watering said web between the wires.

3. The method of making a fibrous web which comprises flowing a turbulent stream of dilute watery unformed fibrous stock with random dispersed fibers to a narrow elongated tapered gap defined by opposed coacting web-forming looped wires, moving the wires toward the narrow end of the gap, supporting the wires at the entrance mouth of the gap upstream from the narrow end of the gap on foraminous rolls having longitudinally extending cells around the periphery thereof adapted to receive water from the wires supported thereon, draining water from the flowing stock through the wires into said cells, depositing fibers in random dispersed condition from said flowing stock onto both of said wires as the water is drained therethrough into said cells, controlling the depth of the flowing stream of stock in said entrance mouth of the gap in accordance with the depth of the bottom of the cells as they enter said mouth of the gap to maintain the stream substantially intact at the same depth while moving the wires on the rolls through the stream toward each other, conveying water in said cells away from said wires, discharging the water from the cells through the peripheries of the rolls, collecting the discharged water out of contact with the wires, and squeezing the wires toward each other to further dewater the fibers therebetween and form a unitary web.

4. The method of making a fibrous web which comprises delivering a turbulently flowing stream of dilute watery fibrous stock at high velocity to a narrow elongated tapering gap having an entrance mouth upstream from the narrow end of the tapering gap defined by upper and lower endless forming wires trained over rolls, at least one roll having a wire trained therearound being provided with cells around the periphery thereof, rotating the rolls and moving the wires therewith in a direction toward the narrow end of the tapering gap at speeds to maintain the turbulent flow of the stock stream in the gap, draining water from the stock in the entrance mouth of the gap through said wires and into the cells of said one roll to deposit fibers in random dispersed condition on both wires, continuing draining water from the gap downstream from the entrance mouth, building up a web inwardly from both wires as the wires advance toward the narrow end of the gap, evacuating said cells as they advance through the gap to hold water from the stock in the cells, separating the wires from the rolls, discharging water outwardly from the cells away from the wires, urging the wires toward each other to interlock the fibers of the web therebetween, and removing additional water from the web.

5. A paper making machine which comprises a looped top forming wire having a bottom forming run, a looped bottom forming wire having a top forming run closely below said bottom run and coating therewith to form a narrow elongated gap therebetween, a pair of cellular faced rolls in the loops of said wires at one end of said loops and having the wires trained therearound to provide an entrance mouth to the gap between the wires, a stock inlet adapted to flow a stream of stock into said entrance month between said wires, the cells of said rolls receiving water drained through the wires from said stream of stock, press rolls urging the active runs of the wires toward each other downstream from said entrance mouth and rolls to further de-water fibers between the wires from said inlet, save-all collectors in the loops of said wires adjacent said cellular rolls to receive water from the roll cells and prevent rewetting of the wires with said water, and said cellular rolls having suction areas along said entrance mouth to evacuate the cells and hold the water therein as the wires advance toward the press rolls.

6. A web-forming machine which comprises upper and lower looped web-forming wires having an elongated narrow gap therebetween, opposed cellular suction rolls in the loops of the wires at one end of said loops receiving the wires therearound and defining a converging entrance to said gap between the wires, rolls at the opposite ends of the loops of said wires cooperating with the cellular rolls to provide opposed forming runs of the wires, press rolls acting on said forming runs of the wires to de-water fibrous web material between the wires, means for flowing a stream of stock into the entrance mouth of said gap between the wires and cellular rolls, means directing the wires away from the cellular rolls beyond said entrance mouth, save-all collectors in the loops of the wires adjacent the cellular rolls to receive water from the roll cells, and means for evacuating the roll cells to hold the water therein received from the stream of stock until the wires leave the rolls.

7. A web making machine which comprises top and bottom looped forming wires having opposed forming runs, a cellular suction roll in the loop of each wire receiving the wire in trained relation therearound to define an entrance mouth to a gap between the wires, an upwardly and rearwardly sloping chute in the loop of the top wire downstream from the cellular roll to coact with the cellular roll and form a tapering gap from said entrance mouth to the bottom forward end of the chute, means for driving the rolls and wires toward said chute, save-all collectors in the loops of the wires adjacent the cellular rolls to receive water from the roll peripheries, means for flowing a stream of stock into the entrance mouth between the wires supported on the cellular rolls for flow through said tapering gap, means for evacuating the cells of the roll along the entrance mouth of said tapering gap to hold water drained from the wires in said roll cells, drainage means coacting with the upper rearward end of said chute to receive water cascade-d over the chute from the top forming Wire, and means downstream from said chute squeezing said wires together to de-water a fibrous web formed between the wires.

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